Simultaneous Observation of Silicon and Boron Impurity Behaviors in the Core Region of a Mid-Density LHD Plasma

Naoki TAMURA, Mikirou YOSHINUMA, Katsumi IDA, Chihiro SUZUKI, Motoshi GOTO, Tetsutarou OISHI, Mamoru SHOJI, Kiyofumi MUKAI, Hisamichi FUNABA
2021 Plasma and Fusion Research  
Line emissions from both silicon (Si) and boron (B) impurity ions introduced by a single tracer-encapsulated solid pellet (TESPEL) containing silicon hexaboride (SiB 6 ) powders were successfully observed using the extreme ultraviolet (EUV) spectrometer and charge-exchange spectroscopy (CXS) technique in the Large Helical Device. The CXS diagnostic shows clearly that a hollow radial profile of fully ionized B impurities was created immediately after the TESPEL injection, and such a hollow
more » ... e was relaxed with time. At the same time, Li-like emissions from the highly ionized Si impurities were also observed with the EUV spectrometer, SOX-MOS. Therefore, the decay times of these impurities could be estimated under the same plasma conditions. The estimated decay time of the Si impurities, τ Si = 0.12 ± 0.01 s, was found to be slightly longer than that of the B impurities, τ B = 0.09 ± 0.01 s.
doi:10.1585/pfr.16.1202094 fatcat:e3tuki6wavhwblkefyhti5bdky